My system crashed, after reinstalling Nvidia drivers(with Maverick Meercat.) -Could not resolve problem, and have done a clean installation of Ubuntu 9.10. Now I would like to upgrade to 12.04. I had so many problems with Unity Desktop, following installation of Natty Narwhal that I gave up, and chose to upgrade to Maverick Meercat (10.10.) How should I proceed?
If you want to upgrade from Maverick to Precise, you have to update the whole system three times. That means, three huge package downloads, three installations, three cleanings, three reboots, and so on. AFAIK there is no (safe) way to upgrade by more than one version at time. If I were you, given that you have a clean installation and then you didn't modify too much, I'll directly install Ubuntu 12.04 (deleting the old partition first) where there was the old installation.
The (really) unsafe way to upgrade the system by more than one version is:
You must be very expert and very lucky for this process to complete without throwing away the installation. Don't try this at home.
If you are running from a clean install of 9.10 and have no settings to be lost it might be faster/easier to just download an .iso for 12.04 and install it from a liveCD or liveUSB.
I've generally always found clean installs better than upgrades when I don't have custom settings/applications to be lost.